Here is something I've been pondering. As far as I'm aware, we have no canon confirmation of which galaxies are the Five Galaxies of the Uplift saga. Looking into it, I've had trouble trying to reason out what they might be, and was wondering whether others have tried to reason it out, as well.
First and foremost, I think it's reasonable to assume that the Five Galaxies are not merely the Milky Way and four of its satellites. The other four galaxies besides our own are all spoken of in a way which would seem to imply that they were also parent galaxies, and when the emblem which was found on the ships in the Shallow Cluster is mentioned it is said to have additional spiral arms and ellipses included (implying, as I recall, that one spiral arm on the emblem = one spiral galaxy, and each ellipse representing an elliptical galaxy including in the united civilization of oxy-life at that time).
So, assuming these galaxies are all independent galaxies, and not satellites (or in the case of Triangulum, is large enough to be "major" even though it may be orbiting Andromeda), which ones are they?
I think it is most reasonable to assume that they would all be relatively close together. There are three large galaxies in our Local Group (the Milky Way, Andromeda, and Triangulum), as well as two on the inner edge of the Sculptor Group (NGC 300 and NGC 55). This would give us our Five Galaxies.
However, when we then start talking about the separation of Galaxy Four from the other connected galaxies, we are in a bit of a hairy situation. Why? Because it seems unlikely that either NGC 300 or NGC 55, a gravitationally-bound pair, would split off without the other, and the same goes for the gravitationally-bound Andromeda and Triangulum galaxies. While we do not know much about exactly how transfer threads/points work, gravity would seem to be as good an explanation as any other, and it would be a little less likely to assume the Five Galaxies are spread across space with other, inaccessible galaxies in between them.
The next two closest galaxies of significant size are Dwingeloo 1 and Maffei 2, but these, too, are relatively proximity to each other (though I honestly don't know enough about them to know if there are gravitational effects between them) and would also have other galaxies in close proximity to them in the IC 342/Maffei Group.
I would be very interested in hearing other thoughts on this!